Patent GB-607863-A (GB)
Title: Improvements in or relating to control systems for hydraulically driven change-speed gears
IPC: F16H63/02
Filed: 1944-12-28
Abstract: 607,863. Controlling change-speed gears; friction clutches. BRUNKEN, R. Dec. 28, 1944, No. 25998. Addition to 606,657. [Class 80 (ii)] [Also in Group XXIX] In a hydro-mechanical transmission system, e.g. for a motor-vehicle, as claimed in the parent Specification, wherein the direct-drive jaw-clutch 48, Fig. 3, of a two-speed countershaft gear, is automatically controlled by a differentially-driven centrifugal shift-governor 95, Fig. 13, responsive to the speed of slip in a hydrokinetic torque-converter 24 or coupling through which the gear is driven, and there is a second differentially-driven centrifugal synchronising- governor 103, responsive to the difference in speeds of the driving and driven shafts 27, 51 of the gear, to synchronise the upshift only, there is now provided a third centrifugal governor 99, responsive only to the speed of the final driven shaft 51 to effect an automatic downshift from direct-drive when the driven shaft stops, so that the subsequent start is made in reduced drive. There is also provided a reversely-acting over-running roller clutch 35 directly connecting the converter driven shaft 27 with the engine crank-shaft 13, which transmits engine braketorque and also ensures that the shift-governor 95 cannot be driven reversely. The driving-wheel 24 of the hydraulic transmitter may be connected directly to the engine-flywheel 11 (as in Fig. 21, not shown), or it may, as shown in Fig. 3, be driven through a branched epicyclic-gear and centrifugal friction-clutch, comprising a driven sun 22, fast to the driving pump-wheel 24, and engaging a clutchdriven ring-gear 19 through intermeshing planet-pairs carried by the driven shaft 27 of the transmitter. The transmitter shown is a threeelement torque-converter, and backward rotation of its reaction-wheel 37 is prevented by an over-running roller detent 41. The centrifugal clutch comprises friction shoes 18, Figs. 3 and 4, radially guided in a cage 17 secured to the driving flywheel 11, and pressed radially inwards into engagement with the outer periphery of the driven ring-gear 19 by pivoted masses 14 having cam-feet engaging rollers 16 on the shoes 18 and pressed inwards by surrounding garter-springs. The countershaft two-speed and reverse gear is the same as that in the parent Specification, comprising a loose wheel 49, jaw-clutched at 53 to the final driven shaft 51 in all forward speeds, and driven in reduced speed from the aligned driving shaft 27 through wheel-pairs 46, 56 and 61, 49, the countershaft wheel 61 having a roller-clutch 63 which over-runs when the direct-drive jawclutch 48, splined to the wheel 49 is clutched directly to the driving wheel 46. A second loose wheel 54, meshing through an idler with a countershaft-wheel 69, is clutched to the driven shaft 51 for reverse by the splined doublejaw clutch 53, which is operated by a forwardneutral-reverse hand-lever 75, Fig. 13. As in the parent Specification the shift-governor 95, Fig. 13, is differentially driven through flexible shafts 85, 89 and worm-gears from the driving and driven sides of the converter, whilst the synchronising-governor 103 is similarly driven from the driving and driven sides of the changespeed gear. The third governor 99 is driven only by the final driven shaft 51. The three governors jointly control switch-contacts through which is energised a solenoid 115 for opening a shift-valve 116 supplying pressure-air from a tank 77 to a cylinder 76 which moves a shift-fork 81, Figs. 3 and 13, to engage the jaw-clutch 48 for direct-drive. Breaking the solenoid-valve circuit vents the shift-cylinder 76 and permits a spring 120 to disengage the direct-drive clutch 48. This occurs when the engine-ignition switch 106 is opened; when the lever 75 is moved to neutral or reverse, opening contacts a, and when the final driven shaft 51 stops, causing collapse of the third governor 99 and opening of contacts b, the three contactsets 106, a and b being arranged in series between a battery B and the supply-line 202 of the shift-circuits. Thus when the vehicle is operated forwardly after any of these three operations, the countershaft roller-clutch 63 automatically picks up reduced drive. Fig. 13 shows the parts in their initial position with the vehicle at rest, the direct-drive shift-fork 81 being in the disengaged position and the lever 75 set for forward drive. Speeding the engine engages the centrifugal clutch 18 and converter 24, starting the vehicle in reduced drive, whereupon the third governor 99 closes the contacts b energising the shift-circuit supplyline 202. Converter-slip during starting causes the shift-governor 95 to open contacts g and close contacts d, whilst the dissimilar speeds of driving and driven shafts of the gear cause the synchronising governor 103 to open contacts c. As load conditions in reduced drive permit the converter to approach minimum slip, the shiftgovernor 95 collapses (position shown), opening contacts d and closing g, which completes a circuit through lead 206, shift-operated contacts h and lead 207 to energise a solenoid 110 which closes the engine-throttle 113. The consequent retardation of the driving shaft synchronises it with the driven shaft, whereupon the synchronising-governor 103 collapses (position shown), closing contacts c and completing a circuit from the supply-line 202, through a switch-arm 109, contact k, lead 203, synchronising-governor contacts c, and lead 204, to energise the shift-valve solenoid 115 supplying pressure-air to the cylinder 76 which shifts the fork 81 to engage the direct-drive clutch 48, and at the same time operates a switch-plunger 117 which opens the contacts h, de-energising the solenoid 110 and allowing a return-spring to re-open the throttle, thus completing the upshift to direct-drive. At the same time the swith-plunger 117 closes contacts e, leading to a switch-solenoid 122. When subsequently increased load conditions create sufficient converter-slip to cause the shift-governor 95 to break the contacts g and make d, a circuit is completed from the supply-line 202, through a lead 205, contacts d, lead 209, and shift-operated contacts e to energize the switch-solenoid 122 which moves the switch arms 109, 124 into engagement with contacts f, j respectively. The arm 124 energizes the throttle-closing solenoid 110 directly from the supply-line 202, whilst breaking the contact k by the arm 109 deenergizes the shift-valve solenoid 115, thus relieving the direct drive clutch 48 of torque- and engaging-load, so that it can be disengaged by the spring 120, thus de-synchronising the gear and causing the synchronising governor 103 to open the contacts c. At the same time the shift-operated switch-plunger 117 closes the contacts h and opens e, which de-energizes the switch-solenoid 122, permitting the switcharms 109, 124 to return to the position shown, ready for the next upshift, and also breaking the circuit of the solenoid 110 to allow the throttle to be re-opened for picking-up reduced drive through the countershaft roller clutch 63.